Five men were arrested on Tuesday for allegedly trafficking drugs and weapons via hidden online marketplaces, the Dutch Public Prosecution Service said Wednesday.

Three men were arrested on Tuesday in the Netherlands on suspicion of setting up and managing the hidden online market place Utopia, a Silk Road clone that the Dutch police seized on Tuesday, Public Prosecution Service spokesman Wim de Bruin said.

The suspects allegedly set up Utopia after another hidden marketplace, Black Market Reloaded, was taken offline at the end of last year when it experienced a large influx of visitors after the U.S. government seized the site of its biggest competitor, Silk Road, in October, the Public Prosecution Service said in a news release. The suspects allegedly had used Black Market Reloaded for dealing in drugs and weapons, it added.

During a search of the suspect's homes the police seized computers, external hard drives and USB sticks as well as about 900 bitcoins worth about a!400,000 to a!600,000 (US$543,000 to $814,000), it said.

The hidden websites were only accessible through the Tor anonymity network, it said.

Utopia's servers were confiscated on Tuesday in Bochum, Germany, and DA1/4sseldorf, the prosecution said. After seizing the servers the police put a warning notice online that reads: "This hidden service has been seized by the Dutch National Police."

Citing the ongoing investigation, De Bruin declined to say how the police managed to locate Utopia's servers.

However, the Dutch police has infiltrated hidden Tor-sites before. In 2011, for example, they managed to seize four hidden sites used to exchange child pornography by obtaining the administrator rights to those sites, according to the prosecution.

The Dutch authorities worked closely with the German Bundeskriminalamt, the Federal Criminal Police Office, which on Tuesday arrested a 21-year-old man on suspicion of dealing in drugs, weapons, munitions as well as stolen credit and debit cards via the marketplaces, De Bruin said. The Dutch have asked the Germans to extradite the suspect to the Netherlands.

A fifth suspect, a Dutchman who was already detained in October for transporting drugs including cocaine and amphetamine to Germany, was arrested again in his cell on Tuesday this time for involvement in illegal trade on the Internet as well as an attempt at inciting a murder, the prosecution said.

The Dutch police used undercover agents to make contact with the suspects and they were able to buy narcotics and firearms, including ecstasy and cocaine, the prosecution said.

"To the astonishment of the police and the Public Prosecution Service," the suspects also asked the undercover agents to extort and murder a person, according to the Prosecution Service. The contact led to a meeting where a deposit was made, according to the prosecution.

The arrests and the seizures are part of a worldwide crackdown on hidden online marketplaces on the Tor-network that started in 2013, the prosecution said.

The men who were arrested in the Netherlands are scheduled to appear before a judge on Friday.

Loek is Amsterdam Correspondent and covers online privacy, intellectual property, open-source and online payment issues for the IDG News Service. Follow him on Twitter at @loekessers or email tips and comments to loek_essers@idg.com

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